com.google.web.bindery.event.gwt.rebind.binder.EventBinderGenerator.java Source code

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Here is the source code for com.google.web.bindery.event.gwt.rebind.binder.EventBinderGenerator.java

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/*
 * Copyright 2013 Google Inc.
 * 
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not
 * use this file except in compliance with the License. You may obtain a copy of
 * the License at
 * 
 * http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 * License for the specific language governing permissions and limitations under
 * the License.
 */
package com.google.web.bindery.event.gwt.rebind.binder;

import com.google.gwt.core.ext.Generator;
import com.google.gwt.core.ext.GeneratorContext;
import com.google.gwt.core.ext.TreeLogger;
import com.google.gwt.core.ext.TreeLogger.Type;
import com.google.gwt.core.ext.UnableToCompleteException;
import com.google.gwt.core.ext.typeinfo.JClassType;
import com.google.gwt.core.ext.typeinfo.NotFoundException;
import com.google.gwt.core.ext.typeinfo.TypeOracle;
import com.google.gwt.user.rebind.ClassSourceFileComposerFactory;
import com.google.gwt.user.rebind.SourceWriter;
import com.google.web.bindery.event.shared.EventBus;
import com.google.web.bindery.event.shared.HandlerRegistration;
import com.google.web.bindery.event.shared.binder.EventBinder;
import com.google.web.bindery.event.shared.binder.GenericEvent;
import com.google.web.bindery.event.shared.binder.impl.AbstractEventBinder;
import com.google.web.bindery.event.shared.binder.impl.GenericEventHandler;

import java.io.PrintWriter;
import java.util.LinkedList;
import java.util.List;

/**
 * Generator for {@link EventBinder}. Takes care of the ugly parts of creating 
 * the source writer and then delegates to {@link EventBinderWriter}. This class
 * is used by the GWT compiler and should not be referenced directly by users.
 *
 * @author ekuefler@google.com (Erik Kuefler)
 */
public class EventBinderGenerator extends Generator {

    @Override
    public String generate(TreeLogger logger, GeneratorContext context, String typeName)
            throws UnableToCompleteException {
        try {
            JClassType eventBinderType = context.getTypeOracle().getType(typeName);
            JClassType targetType = getTargetType(eventBinderType, context.getTypeOracle());
            SourceWriter writer = createSourceWriter(logger, context, eventBinderType, targetType);
            if (writer != null) { // Otherwise the class was already created
                new EventBinderWriter(logger,
                        context.getTypeOracle().getType(GenericEvent.class.getCanonicalName()))
                                .writeDoBindEventHandlers(targetType, writer, context.getTypeOracle());
                writer.commit(logger);
            }
            return getFullyQualifiedGeneratedClassName(eventBinderType);
        } catch (NotFoundException e) {
            logger.log(Type.ERROR, "Error generating " + typeName, e);
            throw new UnableToCompleteException();
        }
    }

    private JClassType getTargetType(JClassType interfaceType, TypeOracle typeOracle) {
        JClassType[] superTypes = interfaceType.getImplementedInterfaces();
        JClassType eventBinderType = typeOracle.findType(EventBinder.class.getCanonicalName());
        if (superTypes.length != 1 || !superTypes[0].isAssignableFrom(eventBinderType)
                || superTypes[0].isParameterized() == null) {
            throw new IllegalArgumentException(interfaceType + " must extend EventBinder with a type parameter");
        }
        return superTypes[0].isParameterized().getTypeArgs()[0];
    }

    private SourceWriter createSourceWriter(TreeLogger logger, GeneratorContext context, JClassType eventBinderType,
            JClassType targetType) {
        String simpleName = getSimpleGeneratedClassName(eventBinderType);
        String packageName = eventBinderType.getPackage().getName();
        ClassSourceFileComposerFactory composer = new ClassSourceFileComposerFactory(packageName, simpleName);

        composer.setSuperclass(
                AbstractEventBinder.class.getCanonicalName() + "<" + targetType.getQualifiedSourceName() + ">");
        composer.addImplementedInterface(eventBinderType.getName());

        composer.addImport(EventBinder.class.getCanonicalName());
        composer.addImport(EventBus.class.getCanonicalName());
        composer.addImport(GenericEvent.class.getCanonicalName());
        composer.addImport(GenericEventHandler.class.getCanonicalName());
        composer.addImport(HandlerRegistration.class.getCanonicalName());
        composer.addImport(LinkedList.class.getCanonicalName());
        composer.addImport(List.class.getCanonicalName());

        PrintWriter printWriter = context.tryCreate(logger, packageName, simpleName);
        return (printWriter != null) ? composer.createSourceWriter(context, printWriter) : null;
    }

    private String getSimpleGeneratedClassName(JClassType eventBinderType) {
        return eventBinderType.getName().replace('.', '_') + "Impl";
    }

    private String getFullyQualifiedGeneratedClassName(JClassType eventBinderType) {
        return new StringBuilder().append(eventBinderType.getPackage().getName()).append('.')
                .append(getSimpleGeneratedClassName(eventBinderType)).toString();
    }
}